Comparative Evaluation of Aspirin Purity Using Titration, Infrared (IR), and Nuclear Magnetic Resonance (NMR) Spectroscopy: A Multi-Technique Quality Control Study

Abstract

Ensuring the chemical stability and purity of over-the-counter pharmaceuticals remains a global priority for public health. This study presents a comparative, multi-modal evaluation of commercial acetylsalicylic acid (aspirin) products sourced from Egypt (M), Turkey (B), and the United Kingdom (H). Ninety-three samples were assessed using three analytical techniques: acid-base titration at three NaOH molarities (0.1 M, 0.2 M, 0.5 M), Fourier-transform infrared (FTIR) spectroscopy, and proton nuclear magnetic resonance (1H-NMR) spectroscopy. Manufacturer H exhibited the highest mean purity and structural consistency, followed by B and M. FTIR confirmed the integrity of functional groups, while 1H-NMR sensitively detected degradation products. The integration of classical and spectroscopic tools highlights the importance of orthogonal analytical strategies for pharmaceutical quality assurance and regulatory compliance.